Systems and methods for delivering aqueous pearlescent digital printing ink compositions using digital offset lithographic printing techniques

ABSTRACT

A system and method are provided for producing variable pearlescent image elements or portions on image receiving media substrates using a variable digital data offset lithographic architecture which provides for varying lithographic images between cycles of a marking device. Pearlescent inks are provided with a solid particle pearlescent pigment components in a proportion of at least 10% by weight suspended in solution in an ink composition. Pearlescent inks are provided with a solid particle pearlescent pigment components having particle sizes in excess of ten microns suspended in solution in the ink composition. The disclosed systems and methods provide for variable pearlescent image elements or portions to be formed on an image receiving medium substrate separate from, or in combination with, other ink image elements or portions applied using other inks in a single device, and/or in a single pass of the image receiving media substrates through an image forming system.

This application is related to U.S. patent application Ser. No.13/907,823, entitled “Systems and Methods For Facilitating Magnetic InkCharacter Recognition (MICR) Image Forming Using Digital OffsetLithographic Techniques” filed on May 31, 2013, which issued as U.S.Pat. No. 8,974,051 on Mar. 10, 2015, the disclosure of which is herebyincorporated by reference herein in its entirety.

BACKGROUND

1. Field of Disclosed Subject Matter

This disclosure relates to systems and methods that provide an abilityto deliver high quality variable pearlescent ink images on successivesubstrates using a proposed variable digital offset lithographic imageforming architecture.

2. Related Art

The visual phenomenon known as pearlescence refers generally to alimitedly iridescent response of a prepared surface to incident light.Pearlescent surfaces reflect incident light in a manner that appears tochange color like the surface of a pearl as the angle of view of thesurface or the angle of illumination by the incident light on thesurface changes. The broader iridescent visual phenomenon is commonlyobserved from surfaces including soap bubbles, butterfly wings, and seashells.

Pearlescent coatings or pigments, which may be deliverable as paints orinks provide the pearlescent visual effect for decorative or ornamentalpurposes using printable products and/or industrial coatings or paints.A common contemporary example of the decorative use of the pearlescentvisual phenomenon, and more broadly the iridescent visual phenomenon, isin its application in paint formulations used by the automotive industryto give cars a lustrous, metallic color changing (or chameleon-like)appearance.

Efforts to extend the concepts of delivering pearlescent images tosurfaces in the printing arts have seen limited success. Printedpearlescent products have been explored not only for the decorativeproperties that the pearlescent printed materials provide, but also fortheir potential security properties in providing a capability touniquely mark a document for identification in a manner that may be moredifficult, for example, for a counterfeiter to reproduce.

The pearlescent effect on printed products can be difficult to generatebecause the metallic sheen is generated through the use of comparativelylarge solid pigment particles, on the order of tens of microns, whichare difficult to stabilize in an ink composition. Digital printing usingpearlescent inks is very difficult using conventional digital imagingtechniques as the pearlescent inks prove nearly impossible to jet basedon the necessary particle sizes appropriate to produce the pearlescenteffect in the finished documents.

Pearlescent inks can be used to form printed materials usingconventional lithographic and offset lithographic printing techniques.These techniques, however, use plates that are permanently patterned,and are, therefore, generally considered to be most useful only whenprinting a same image in long print runs. Conventional lithographictechniques, while suitable for producing pearlescent images ondocuments, are generally not considered amenable to creating andprinting a new pattern from one page to the next because, according toknown methods, removing and replacing of plates, including on a printcylinder, is required in order to change images. Because conventionallithographic techniques cannot accommodate true high speed variable dataprinting processes in which the images to be printed change fromimpression to impression, for example, as in the case of digitalprinting systems, these techniques do not provide an opportunity toeffectively and/or economically produce pearlescent images on documentsthat change from page to page or across small runs of pages.

Typically, ink jet printing techniques are considered to be mostamenable to high speed variable data digital image forming. A shortfallfor certain printing applications, including pearlescent image forming,is that the physical compositions of the jetted inks must be carefullycontrolled within fairly rigid parameters. Generally, jetted inks cannotbe particularly viscous and/or they cannot contain solid pigmentparticles over a certain size. Overly viscous ink compositions, or inkcompositions having solid particles with larger particle sizes, willtend to very easily clog the jets and introduce other issues thatadversely affect image forming operations through the ink jettingprocess supporting the digital printing. Producing jet nozzles withsufficient diameters to prevent this clogging is not reasonably feasiblebased on the array of other physical and operational characteristicsthat appropriately large nozzles would introduce.

The preparation of jettable inks often involves extensive pulverizationof the solid elements, such as the pigments or other solids included inthe ink compositions, with, for example, steel shot or in a grinder(high speed media mill), in order that the solid elements are moreeasily suspended in the liquid thus making them easier to pass in theink jetting process.

A difficulty arises in the compatibility of the pearlescent printingscheme with inks prepared by pulverizing the solid elements in that thepearlescent properties will be lost if the pearlescent pigment particlesare pulverized to an appropriately jettable size. To preserve thevariable reflectivity of the pearlescent finish, or to make the finishedsurfaces pearlesce, it is easily understood that a larger reflectingsurface for each of the constituent particles is preferred. In factthose of skill in the art recognize that, in order to preserve thepearlescent phenomenon in a printed image, the solid pearlescent pigmentparticles need to be on the order of ten of microns in diameter, eachrepresenting a little shiny mirror in the ink.

A desire to form variable digitally produced pearlescent images onsuccessive image receiving medium substrates conflicts with thepractical need in preparing jettable inks to pulverize the solids intoas small a size as possible for those constituent elements of thejettable inks. When this requirement for pulverization is combined witha concern that only limited amounts of any pigment solids can be addedto the jettable ink solution without adversely affecting the viscosityof the jettable ink solution, it becomes clear that producing highquality digital pearlescent images in a conventional digital printingprocess using jettable inks is nearly impossible. These limitations thatmay keep the advantages of pearlescent image forming for printeddocuments from being fully realized and exploited.

SUMMARY OF THE DISCLOSED EMBODIMENTS

U.S. Patent Application Publication No. 2012/0103212 A1 (the 212Publication) published May 3, 2012 and based on U.S. patent applicationSer. No. 13/095,714, which is commonly assigned and the disclosure ofwhich is incorporated by reference herein in its entirety, proposessystems and methods for providing variable data lithographic and offsetlithographic printing or image receiving medium marking. The systems andmethods disclosed in the 212 Publication are directed to improvements onvarious aspects of previously-attempted variable data imaginglithographic marking concepts based on variable patterning of fountainsolutions to achieve effective truly variable digital data lithographicprinting.

According to the 212 Publication, a reimageable surface is provided onan imaging member, which may be a drum, plate, belt or the like. Thereimageable surface may be composed of, for example, a class ofmaterials commonly referred to as silicones, includingpolydimethylsiloxane (PDMS) among others. The reimageable surface may beformed of a relatively thin layer over a mounting layer, a thickness ofthe relatively thin layer being selected to balance printing or markingperformance, durability and manufacturability.

The 212 Publication describes, in requisite detail, an exemplaryvariable data lithography system 100 such as that shown, for example, inFIG. 1. A general description of the exemplary system 100 shown in FIG.1 is provided here. Additional details regarding individual componentsand/or subsystems shown in the exemplary system 100 of FIG. 1 may befound in the 212 Publication.

As shown in FIG. 1, the exemplary system 100 may include an imagingmember 110. The imaging member 110 in the embodiment shown in FIG. 1 isa drum, but this exemplary depiction should not be read in a manner thatprecludes the imaging member 110 being a plate or a belt, or of anotherknown configuration. The imaging member 110 is used to apply an inkimage to an image receiving media substrate 114 at a transfer nip 112.The transfer nip 112 is produced by an impression roller 118, as part ofan image transfer mechanism 160, exerting pressure in the direction ofthe imaging member 110. Image receiving medium substrate 114 should notbe considered to be limited to any particular composition such as, forexample, paper, plastic, or composite sheet film. The exemplary system100 may be used for producing images on a wide variety of imagereceiving media substrates. The 212 Publication also explains the widelatitude of marking (printing) materials that may be used, includingmarking materials with pigment densities greater than 10% by weight. Asdoes the 212 Publication, this disclosure will use the term ink to referto a broad range of printing or marking materials to include those whichare commonly understood to be inks, pigments, and other materials whichmay be applied by the exemplary system 100 to produce an output image onthe image receiving media substrate 114.

The 212 Publication depicts and describes details of the imaging member110 including the imaging member 110 being comprised of a reimageablesurface layer formed over a structural mounting layer that may be, forexample, a cylindrical core, or one or more structural layers over acylindrical core.

The exemplary system 100 includes a fountain solution subsystem 120generally comprising a series of rollers, which may be considered asdampening rollers or a dampening unit, for uniformly wetting thereimageable surface of the imaging member 110 with fountain solution. Apurpose of the fountain solution subsystem 120 is to deliver a layer offountain solution, generally having a uniform and controlled thickness,to the reimageable surface of the imaging member 110. The fountainsolution may comprise mainly water optionally with small amounts ofisopropyl alcohol or ethanol added to reduce surface tension as well asto lower evaporation energy necessary to support subsequent laserpatterning, as will be described in greater detail below. Small amountsof certain surfactants may be added to the fountain solution as well toadjust the inking and transfer properties of the reimageable surface ofthe imaging member 110.

Once the fountain solution is metered onto the reimageable surface ofthe imaging member 110, a thickness of the fountain solution may bemeasured using a sensor 125 that may provide feedback to control themetering of the fountain solution onto the reimageable surface of theimaging member 110 by the fountain solution subsystem 120.

Once a precise and uniform amount of fountain solution is provided bythe fountain solution subsystem 120 on the reimageable surface of theimaging member 110, and optical patterning subsystem 130 may be used toselectively form a latent image in the uniform fountain solution layerby image-wise patterning the fountain solution layer using, for example,laser energy. The reimageable surface of the imaging member 110 shouldideally absorb most of the laser energy emitted from the opticalpatterning subsystem 130 close to the surface to minimize energy wastedin heating the fountain solution and to minimize lateral spreading ofheat in order to maintain a high spatial resolution capability.Alternatively, an appropriate radiation sensitive component may be addedto the fountain solution to aid in the absorption of the incidentradiant laser energy. While the optical patterning subsystem 130 isdescribed above as being a laser emitter, it should be understood that avariety of different systems may be used to deliver the optical energyto pattern the fountain solution.

The mechanics at work in the patterning process undertaken by theoptical patterning subsystem 130 of the exemplary system 100 aredescribed in detail with reference to FIG. 5 in the 212 Publication.Briefly, the application of optical patterning energy from the opticalpatterning subsystem 130 results in selective evaporation of portions ofthe layer of fountain solution.

Following patterning of the fountain solution layer by the opticalpatterning subsystem 130, the patterned layer over the reimageablesurface of the imaging member 110 is presented to an inker subsystem140. The inker subsystem 140 is used to apply a uniform layer of inkover the layer of fountain solution and the reimageable surface layer ofthe imaging member 110. The inker subsystem 140 may use an anilox rollerto meter an offset lithographic ink onto one or more ink forming rollersthat are in contact with the reimageable surface layer of the imagingmember 110. Separately, the inker subsystem 140 may include othertraditional elements such as a series of metering rollers to provide aprecise feed rate of ink to the reimageable surface. The inker subsystem140 may deposit the ink to the pockets representing the imaged portionsof the reimageable surface, while ink deposited on the unformattedportions of the fountain solution will not adhere based on thehydrophobic and/or oleophobic nature of those portions.

A cohesiveness and viscosity of the ink residing in the reimageablelayer of the imaging member 110 may be modified by a number ofmechanisms. One such mechanism may involve the use of a rheology(complex viscoelastic modulus) control subsystem 150. The rheologycontrol system 150 may form a partial crosslinking core of the ink onthe reimageable surface to, for example, increase ink cohesive strengthrelative to the reimageable surface layer. Curing mechanisms may includeoptical or photo curing, heat curing, drying, or various forms ofchemical curing. Cooling may be used to modify rheology as well viamultiple physical cooling mechanisms, as well as via chemical cooling.

The ink is then transferred from the reimageable surface of the imagingmember 110 to a substrate of image receiving medium 114 using a transfersubsystem 160. The transfer occurs as the substrate 114 is passedthrough a transfer nip 112 between the imaging member 110 and animpression roller 118 such that the ink within the voids of thereimageable surface of the imaging member 110 is brought into physicalcontact with the substrate 114. With the adhesion of the ink having beenmodified by the rheology control system 150, modified adhesion of theink causes the ink to adhere to the substrate 114 and to separate fromthe reimageable surface of the imaging member 110. Careful control ofthe temperature and pressure conditions at the transfer nip 112 mayallow transfer efficiencies for the ink from the reimageable surface ofthe imaging member 110 to the substrate 114 to exceed 95%. While it ispossible that some fountain solution may also wet substrate 114, thevolume of such a fountain solution will be minimal, and will rapidlyevaporate or be absorbed by the substrate 114.

In certain offset lithographic systems, it should be recognized that anoffset roller, not shown in FIG. 1, may first receive the ink imagepattern and then transfer the ink image pattern to a substrate accordingto a known indirect transfer method using an offset roller or otherdevice as an intermediate transfer body.

Following the transfer of the majority of the ink to the substrate 114at the transfer nip 112, any residual ink and/or residual fountainsolution must be removed from the reimageable surface of the imagingmember 110 to prepare the reimageable surface to repeat the digitalimage forming operation. H is removal is most preferably undertakenwithout scraping or wearing the reimageable surface of the imagingmember 110. An air knife or other like non-contact device may beemployed to remove residual fountain solution. It is anticipated,however, that some amount of ink residue may remain. Removal of suchremaining ink residue may be accomplished through use of some form ofcleaning subsystem 170. The 212 Publication describes details of such acleaning subsystem 170 including at least a first cleaning member suchas a sticky or tacky member in physical contact with the reimageablesurface of the imaging member 110, the sticky or tacky member removingresidual ink and any remaining small amounts of surfactant compoundsfrom the fountain solution of the reimageable surface of the imagingmember 110. The sticky or tacky member may then be brought into contactwith a smooth roller to which residual ink may be transferred from thesticky or tacky member, the ink being subsequently stripped from thesmooth roller by, for example, a doctor blade or other like device andcollected as waste.

The 212 Publication details other mechanisms by which cleaning of thereimageable surface of the imaging member 110 may be facilitated.Regardless of the cleaning mechanism, however, cleaning of the residualink and fountain solution from the reimageable surface of the imagingmember 110 is essential to preventing ghosting in subsequent imageforming operations as the images change. Once cleaned, the reimageablesurface of the imaging member 110 is again presented to the fountainsolution subsystem 120 by which a fresh layer of fountain solution issupplied to the reimageable surface of the imaging member 110, and theprocess is repeated.

According to the above proposed structure, variable data digitallithography has attracted attention in producing truly variable digitalimages in a lithographic image forming system. The above-describedarchitecture combines the functions of the imaging plate and potentiallya transfer blanket into a single imaging member 110.

It would be advantageous to adapt the above-described variable digitaldata lithographic printing system to support effective variable digitalpearlescent image forming for printed products delivered to successiveimage receiving media substrates.

Exemplary embodiments of the systems and methods according to thisdisclosure may take advantage of the proposed variable digital datalithographic printing architecture to provide, at once, a speed ofoffset printing and the digital capability of ink jet or xerographicprinting for variable pearlescent image forming on successive individualsubstrates.

Exemplary embodiments may include prepared pearlescent inks based on thecomponents used to make inks for the proposed variable digital datalithographic printing architecture described above. The pearlescent inksmay comprise, for example, greater than 15 percent by weight (andupwards to 50 percent by weight) pigment particles suspended in anaqueous solution to support variable pearlescent image forming.

Exemplary embodiments may provide for pearlescent pigment particles witha particle size of more than ten microns, i.e., 10 to 15 to 20 micronsand greater in size, to ensure the pearlescent effect on the printedproducts to be suspended in an ink solution of compatible products foruse in the variable digital data lithographic printing architecture.

Exemplary embodiments may provide for pearlescent pigment particles tobe suspended in an acrylate ink vehicle that may be water dilutable,with an addition of water being available to adjust and/or enhancebackground performance for use in the variable digital data lithographicprinting architecture.

Exemplary embodiments may support larger volumes of comparatively largerparticle sized pigment elements without concern for the limitationsimposed in conventional digital image forming methods including inkjetting of the pearlescent inks.

Exemplary embodiments may make advantageous use of the characteristicsof digital offset inks that are formulated to contain much higher (up toten times) pigment loading and therefore have higher viscosity at roomtemperature in a variable digital data printing process. The largermetal flake particles of the pearlescent inks would not be pulverized,which would enhance the visual phenomenon of the finished materials.Further, film thicknesses or pile heights may be controlled easily usingthe variable digital data lithographic printing architectures bymodifying the image area of the printing plate. This control of filmthickness may be used to influence the degree of pearlescence observedin the final print image formed on the image receiving medium substrate.

These and other features, and advantages, of the disclosed systems andmethods are described in, or apparent from, the following detaileddescription of various exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the disclosed systems and methods thatprovide an ability to produce high quality pearlescent images onsubstrates using a proposed variable digital offset lithographicarchitecture will be described, in detail, with reference to thefollowing drawings, in which:

FIG. 1 illustrates a schematic representation of a proposed variabledata lithographic printing system;

FIG. 2 illustrates a schematic representation of an exemplary embodimentof an image forming device that may be used to implement variabledigital data pearlescent image forming according to this disclosure;

FIG. 3 illustrates a block diagram of an exemplary embodiment of animage forming system implementing variable digital data pearlescentimage forming according to this disclosure; and

FIG. 4 illustrates a flowchart of an exemplary method for implementingvariable data lithographic printing for pearlescent image forming in aproposed variable data lithographic printing system according to thisdisclosure.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

The systems and methods that provide an ability to produce high qualitypearlescent printed images on substrates in a heretofore unachievablemanner using a proposed variable digital offset lithographicarchitecture according to this disclosure will generally refer to thisspecific utility or function for those systems and methods. Exemplaryembodiments described and depicted in this disclosure should not beinterpreted as being specifically limited to any particularconfiguration of the described image forming elements, or as beingspecifically directed to any particular intended use for those elements.Any advantageous adaptation of a digital image forming process toaccommodate the use of pearlescent inks in, for example, a variable datalithographic printing system that facilitates high quality variableoutput pearlescent images, is contemplated as being included in thisdisclosure.

Specific reference to, for example, lithographic printing techniques,and to the proposed variable data lithographic printing device shouldnot be considered as being limited to any particular configuration ofthe techniques or devices, as described. The terms “image formingdevice,” “offset lithographic printing device/system,” “offsetlithographic marking device/system” and the like, as referencedthroughout this disclosure are intended to refer globally to a class ofdevices and systems that carry out what are generally understood aslithographic marking functions as those functions would be familiar tothose of skill in the art. Additionally, while references will be madeto individual pearlescent ink compositions and the like, thesereferences, and described compositions of constituent elements too, areintended to be exemplary only and not limiting to the disclosed subjectmatter.

Exemplary pearlescent inks have been tested for use in the proposedvariable digital offset lithographic architecture, which has beenreferred to as a “Digital Advanced Lithographic Imaging” or DALI system.In these exemplary pearlescent inks, for example, commercially availablepearlescent pigments were used Inks having a 15 percent by weightpigment were prepared to test the concepts represented in the disclosedschemes. Significantly higher pigment loadings are understood to bewithin the latitude afforded by the use of the disclosed techniques.

A specific component mix that was selected to prove the feasibility ofthe disclosed scheme for variable pearlescent image forming included thefollowing (see Table 1): a pearlescent pigment of Afflair 520 SatinBronze, available from EM Industries Inc.®; curable functional acrylatemonomers, CN 293, CN294E, CN259 and CN454 available from Sartomers®;Solsperse 39,000 dispersant available from Lubrizol®; a thermalstabilizer Irgastab UV10 available from BASF®; optionally aerosol 200 vsavailable from Degussa Canada Ltd®; and a photoinitiator system composedof Irgacure 819, Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide) andIrgacure 184, 1-Hydroxy-cyclohexyl-phenyl-ketone. In embodiments, thephotoinitiator system may contain optionally Irgacure 379,2-Dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one,and Esacure Kip 150, Oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] respectivelyavailable from BASED, BASED, and Lamberti®. Other optional components oradditives may include: 1) polyester oligomers selected from Sartomer®,e.g., CN2255, a high viscosity polyester acrylate oligomer with a glasstransition T of −13° C. and CN2256 also a polyester acrylate oligomerwith viscosity of 11,000 cps at 60° C. and a glass transition T of −22°C.; 2) a hindered amine light stabilizer such as TINUVIN®292; 3) aleveling agent such as Byk 3500, a polyether modified acryl functionalpolydimethylsiloxane; and 4) a defoamer such as Additol VXL 4951available from Cytek®.

TABLE 1 Example 1 Chemical Wt % Mass (g) AFLAIR520 Satin Bronze 15.0030.00 BASF ® Irgalite Magenta SMA 0.00 0.00 Sartomer ® CN2255 (highvisco) 0.00 0.00 Sartomer ® CN2256 7.00 14.00 Ebecryl ® 2003 41.00 82.00Ebecryl ® 11 9.93 19.86 Ebecryl ® 12 17.37 34.74 Solsperse 39000 4.509.00 Additol VXL 4951 2.00 4.00 Irgacure 184 0.00 0.00 Irgacure 819 0.000.00 Ciba Irgastab UV10 0.20 0.40 Aerosil 200 3.00 6.00 Total 100.00200.00

The pearlescent inks produced for experimentation were water dilutable.Water may be added to the pearlescent ink compositions in low levels inorder to adjust the materials' interaction properties with the DALIplate and the plate wetting solutions. A challenge for inks with largepigment sizes is observation of good background Inks of large pigmentsize more easily press through the wetting solution layer with transfer.For the disclosed concepts, experimentation indicates that thebackground effect is mitigated by the addition of water to thepearlescent ink composition.

Produced test pearlescent inks were then printed using a drawdowncoating apparatus for the evaluation of pearlescence, and prints weredemonstrated with a DALI test plate. The produced pearlescent imagesexhibited an acceptable metallic sheen and had a film thickness ofapproximately 60 microns, much thicker than the 0.1 to 5.0 micron filmthicknesses typically experienced in digital printing using, forexample, jettable inks.

As described above, the proposed digital offset printing or DALI processmay involve the transfer of a pigmented UV-curable ink onto afluoro-silicone printing plate which has been partially coated with awetting solution as a release agent. The ink is then optionallypartially cured using UV light and transferred from the plate to thesubstrate, which may be generally unrestricted in its composition toinclude being one or more of a paper, a plastic or a metal. Oncetransfer is complete, the deposited ink images on the substrate may beexposed again to UV light for final curing of the deposited image on thesubstrate.

In order to meet the requirements of the digital offset printing or DALIprocess, the inks that are employed may possess many desirable physicaland chemical properties. The inks must be compatible with materials withwhich they are brought into contact during the DALI process, includingthe printing plate, the wetting solution and the myriad image receivingmedium substrates. The inks must also meet all functional requirementsof the digital offset printing or DALI sub-systems, includingappropriate wetting and transfer properties.

Inks formulated for the digital offset printing or DALI process aredifferent in many ways from other conventional inks used in otherapplications, including conventional pigmented solid inks and otherUV-curable gel inks Digital offset printing or DALI inks generallycontain much higher (up to 10 times) pigment loading and therefore havehigher viscosities at room temperature. This higher pigment loadingprovides an advantage of increased hiding power on printed images.Another advantage of the digital offset printing or DALI inks is thelimited requirement for any particle size reduction to which the solidconstituent components are exposed during processing. Unlike pigmentedjettable inks, which are subjected to high energy impact milling such asthrough attrition or media mills, offset inks are typically processedusing a 3-roll mill, in which particle size is controlled by a number ofpasses, composition of the ink, and processing parameters. Compared withthe jettable inks, larger particles (ten micron-sized and more) in theinks may be tolerated for digital offset printing or DALI processes. Thelatitude in the inclusion of larger particles may support or enablehigher pearlescence in the variably printed products.

The disclosed embodiments propose ink formulations that have beendeveloped to meet the printing requirements for a digital offset or DALIprinter. In embodiments, pearlescent pigments are incorporated into theinks such that they meet these requirements, namely wetting and releaseproperties from the proposed offset plate and compatibility with thenon-aqueous wetting solutions usable with these image forming processes.

A printing demonstration was undertaken by hand testing using test DALIfluoro-silicone plates as the imaging plates and the Example 1formulation shown above in Table 1 with particle size variations of 1-20microns. Example 1 ink was applied by hand roller tofluoro-silicone-over-silicone test DALI plates and was observed to wetthe plates. Application of a wetting solution to the plates was followedby rolling ink over the plates with a roller and then transferring withan even film from the plates to paper. The demonstration resulted ingood background performance for the Example 1 ink. The addition of waterto the pearlescent experimental ink was shown to enable modification inthe background performance. The addition of 30 percent water to the baseformulation displayed background performance close to what wereconsidered to be acceptable levels. At or near 0 percent background isanticipated to be achievable through adjustments in the pearlescent inkformulation.

Pearlescent digital offset inks suitable for the proposed variabledigital data offset lithographic image forming or DALI architectures andsub-systems are proposed using aqueous dilutable, curablecommercially-available components. Many of the reactive monomers oroligomers that were investigated have been shown to be advantageous toenhance performance of printing the specialty ink in a variable digitaldata offset lithographic printing system. The proposed pearlescent inkformulations possess a number of advantages including: suitability foruse with the proposed variable digital data lithographic image formingprocess; adjustable compatibility with the fountain (dampening and/orwetting) solutions and plate materials used for the proposed DALI imageforming devices through use of an aqueous dilutable formulation;impressive settling stability due to high zero shear viscosity; andimproved pearlescence based on the opportunity for high particle pigmentloading and large pigment particle size (>10 microns).

FIG. 2 illustrates a schematic representation of an exemplary embodimentof an image forming device 200 for implementing variable digitalpearlescent image forming according to this disclosure. As shown in FIG.2, individual image receiving medium substrates may be provided in animage receiving medium substrate source 210. The individual imagereceiving medium substrates may be sequentially passed along an imagereceiving medium transport path 215 in direction A.

The individual image receiving medium substrates may be passed frommultiple transfer nips formed between inked imaging rollers 220, 230,240, 250, 260 and the opposing rollers 222, 232, 242, 252, 262 in orderto deposit one or more separate consistencies and colors of inks,including a particularly-formulated pearlescent ink, on at least selectportions of the individual image receiving medium substrates. One ormore of the inked imaging rollers 220, 230, 240, 250, 260 may beconventional lithographic image transfer rollers. At least the one ofthe inked imaging rollers 220, 230, 240, 250, 260 that is configuredand/or designated for the deposition of the pearlescent ink described inthis disclosure may otherwise be an image transfer roller that is partof an individual and separate variable digital data offset lithographicsystem as shown, for example, in FIG. 1. It should be noted that all ofthe imaging rollers to 220, 230, 240, 250, 260 may be an image transferroller that is each a part of an individual and separate variabledigital data offset lithographic system. As each of the one or morecolored inks may be deposited on an individual image receiving mediumsubstrate as that substrate proceeds along the image receiving mediumtransport path 215, each of the deposited one or more colored inks maybe at least partially cured by one or more individual curing devices225, 235, 245, 255, 265.

Those of skill in the art recognize that it is likely that individualportions of a particular image transferred to an image receiving mediumsubstrate may be exclusively reserved to imaging by the one or moreimaging rollers of pearlescent image elements separate and apart fromtext and other multicolor image elements. This disclosure, however,makes no distinction between one or the other of the pearlescent imageelements and the other text and/or multicolor image elements being inany specific background/foreground relationship with respect to oneanother. It is envisioned that pearlescent image elements may beavailable and applied in a manner that may enhance, for example,underlying multicolor imaging elements in certain applications. In thisregard, all combinations of compatible image forming according tovariable digital data input to an exemplary system such as that, forexample, depicted in FIG. 2 may be available. In the variouscombinations of application of individual image forming elements fromone or more imaging rollers, it is anticipated that some amount ofintermediate curing may be undertaken, and that a final curing processis implemented by, for example, a final curing device 265 positioned ata position downstream of all of the imaging rollers prior to ejecting animage receiving medium substrate with an image deposited and curedthereon to, for example, an output tray (not shown).

FIG. 3 illustrates a block diagram of an exemplary embodiment of animage forming system 300 for implementing variable digital datapearlescent image forming according to this disclosure.

The exemplary image forming system 300 may include an exemplary controlsystem 310. All or some of the components of the exemplary controlsystem 310 may be included as integral components of the exemplary imageforming system 300. Otherwise, certain of the components of theexemplary control system 310 for undertaking processing and controlfunctions for the exemplary image forming system 300 may be housed in,for example, a separate computing device that may be associated with theexemplary image forming system 300, and connected, for example, to theexemplary image forming system 300 via a communication link 370, whichmay be constituted of a wired or wireless data connection between theexemplary control system 310 and other components of the exemplary imageforming system 300.

Generally, in the image forming system 300, individual image receivingmedium substrates (sheets) may be provided in an image receiving mediasource 340, which may include, for example, an input image media sourcetray. The image receiving medium substrates may be transported to animage forming and curing device 350, which may be constituted of adigital offset image forming device, where the images are formed bydepositing image marking material separately from one or more imagingrollers, or from separate image marking material sources associated witha single variable digital data imaging roller, on the image receivingmedium substrates. The image receiving medium substrates with the imagesformed, fused and fixed thereon, including pearlescent image elementsaccording to the disclosed concepts being formed, fused and fixedthereon, may be transported to, and deposited in, an image receivingmedia output collection unit 360, such as, for example, an output tray.

The exemplary control system 310 may include an operating interface 315by which a user may communicate with the exemplary control system 310for directing image forming operations, including the forming ofvariable pearlescent image elements, on the image receiving mediumsubstrates in the image forming system 300. The operating interface 315may be a locally accessible user interface associated with the imageforming system 300. The operating interface 315 may be configured as oneor more conventional mechanisms common to control devices and/orcomputing devices that may permit a user to input information to theexemplary control system 310. The operating interface 315 may include,for example, a conventional keyboard, a touchscreen with “soft” buttonsor with various components for use with a compatible stylus, amicrophone by which a user may provide oral commands to the exemplarycontrol system 310 to be “translated” by a voice recognition program, orother like device by which a user may communicate specific operatinginstructions to the exemplary control system 310. The operatinginterface 315 may be a part of a function of a graphical user interface(GUI) mounted on, integral to, or associated with, the image formingsystem 300 with which the exemplary control system 310 is associated.

The exemplary control system 310 may include one or more localprocessors 320 for individually operating the exemplary control system310 and for carrying out operating functions in the image forming system300. Processor(s) 320 may include at least one conventional processor ormicroprocessor that interprets and executes instructions to directspecific functioning of the exemplary control system 310 and imageforming system 300.

The exemplary control system 310 may include one or more data storagedevices 325. Such data storage device(s) 325 may be used to store dataor operating programs to be used by the exemplary control system 310,and specifically the processor(s) 320. Data storage device(s) 325 may beused to store information regarding individual operating characteristicsof the image forming and curing device 350 to, for example, controlimage forming, including pearlescent image forming, in the image formingand curing device 350. These stored schemes may control all operationsof the image forming system 300. The data storage device(s) 325 mayinclude a random access memory (RAM) or another type of dynamic storagedevice that is capable of storing updatable database information, andfor separately storing instructions for execution of system operationsby, for example, processor(s) 320. Data storage device(s) 325 may alsoinclude a read-only memory (ROM), which may include a conventional ROMdevice or another type of static storage device that stores staticinformation and instructions for processor(s) 320. Further, the datastorage device(s) 325 may be integral to the exemplary control system310, or may be provided external to, and in wired or wirelesscommunication with, the exemplary control system 310.

The exemplary control system 310 may include at least one data displaydevice 330, which may be configured as one or more conventionalmechanisms that output information to a user, including, but not limitedto, a display screen on a GUI of the image forming system 300 with whichthe exemplary control system 310 may be associated. The data displaydevice 330 may be used to indicate to a user a status of an imageforming operation in the image forming system 300, or specific operationof the image forming and curing device 350 for executing imaging andpearlescent image element forming operations.

All of the various components of the exemplary control system 310, asdepicted in FIG. 3, may be connected internally, and to the imageforming and curing device 350, by one or more data/control busses. Thesedata/control busses may provide wired or wireless communication betweenthe various components of the exemplary control system 310, whether allof those components are housed integrally in, or are otherwise externaland connected to, other components of the image forming system 300 withwhich the exemplary control system 310 may be associated.

It should be appreciated that, although depicted in FIG. 3 as anessentially integral unit, the various disclosed elements of theexemplary control system 310 may be arranged in any combination ofsub-systems as individual components or combinations of components,integral to a single unit, or external to, and in wired or wirelesscommunication with, the single unit of the exemplary control system 310.In other words, no specific configuration as an integral unit or as asupport unit is to be implied by the depiction in FIG. 3. Further,although depicted as individual units for ease of understanding of thedetails provided in this disclosure regarding the exemplary controlsystem 310, it should be understood that the described functions of anyof the individually-depicted components may be undertaken, for example,by one or more processors 320 connected to, and in communication with,one or more data storage device(s) 330, all of which support operationsin the image forming system 300.

The disclosed embodiments may include an exemplary method forimplementing variable data lithographic printing for pearlescent imageforming in a proposed variable data lithographic printing system. FIG. 4illustrates a flowchart of such an exemplary method. As shown in FIG. 4,operation of the method commences at Step S4000 and proceeds to StepS4100.

In Step S4100, a pearlescent ink may be provided in at least one inksource associated with at least one imaging roller in a variable digitaldata lithographic image forming system. Based on the fact that accordingto this disclosure pearlescent image elements are likely to change fromimage to image, or substrate to substrate, the at least one imagingroller with which the at least one pearlescent ink source is associatedin the variable digital data lithographic image forming system willcomprise a variable data lithography system such as that shown, forexample, in FIG. 1. Operation of the method proceeds to Step S4200.

In Step S4200, digital data describing images to be formed on imagereceiving media substrates by the variable digital data lithographicimage forming system may be obtained. The digital data may be obtained,for example, by user input of information via some form of operatinginterface, or may be recovered from a storage device based on some userinput. In other words, sources of the digital data describing the imagesto be formed on the image receiving media substrates may be obtainedaccording to known methods and provided to the variable digital datalithographic image forming system via wired or wireless communications.The digital data describing the images to be formed on the imagereceiving media substrates may include information regarding pearlescentimage elements to be produced as part of the overall images formed onthe image receiving media substrate, the pearlescent image elementschanging from image to image or substrate to substrate on successiveimage receiving media substrates ordered by digital data pertaining to asingle print task to be carried out by the variable digital datalithographic image forming system. Operation of the method proceeds toStep S4300.

In Step S4300, individual elemental portions of the images on the imagereceiving media substrates may be individually formed using multipleinks of the variable digital data lithographic image forming system. Theindividual inks may be applied using separate imaging rollersassociated, for example, one each with each of the individual inks.Alternatively, the individual inks may be applied using separate cyclesof a single rewritable imaging roller with access to individual inksources for each of the individual inks, including the pearlescent ink.When using multiple imaging rollers, the multiple imaging rollers, otherthan the pearlescent ink imaging roller, may be associated with separateimage forming modules that may be variable digital data lithographicimage forming modules, or may be associated with separate image formingmodules that may be conventional lithographic image forming modules, theimaging rollers including, for example, semi-fixed plates on imagingdrums.

It is envisioned that, although the variable data lithography systemshown in exemplary manner in FIG. 1 is generally depicted and describedas a single color image forming module, advances in the variable datalithography system may provide for producing multicolor images using asingle reimageable surface on a single imaging member as shown. In suchinstances, separate cycles of the imaging member may introduce markingmaterials of differing colors. Operation of the method proceeds to StepS4400.

In Step S4400, some or each of the individual elemental portions of theimages formed on the image receiving media substrates as a single color,or in multiple colors, may be at least partially cured in a manner thatfixes the individual elemental portions of the images on the imagereceiving media substrates. This partial curing may prove particularlyadvantageous in a variable digital data lithographic image formingsystem in which the image receiving media substrates are subjected tomultiple image transfers at multiple image forming nips, or in multiplecycles of a single image forming nip. Partial curing of the portions ofthe images transferred to the image receiving media substrate atprevious stages in the image forming processes will reduce, orsubstantially eliminate, a potential for back transfer of the alreadydeposited individual elemental portions of the images subsequent imageforming nips or on separate cycles through a same image forming nip.Operation of the method proceeds to Step S4500.

In Step S4500, the total images, including the pearlescent imageportions, may be ultimately cured and/or fused on the image receivingmedia substrates with at least one final cured device downstream of theone or the last imaging roller in the variable digital data lithographicimage forming system that forms the images, including the pearlescentimage elements or portions on the image receiving media substrates.Operation the method proceeds to Step S4600.

In Step S4600, the image receiving media substrates, with the finalcured images, including the pearlescent image elements or portions,formed thereon may be output from the variable digital data lithographicimage forming system. Operation the method proceeds to Step S4700, whereoperation of the method ceases.

The above-described exemplary systems and methods may reference certainconventional lithographic image forming device components to provide abrief, background description of image forming means that may bemodified to carry out variable digital data lithographic image formingfor images which include, at least in part, images formed usingpearlescent inks, in a system using a unique imaging forming technique.No particular limitation to a specific configuration of the variabledata lithography portions or modules of an overall variable digital datalithographic image forming system is to be construed based on thedescription of the exemplary elements depicted and described above.

Those skilled in the art will appreciate that other embodiments of thedisclosed subject matter may be practiced with many types of imageforming elements common to lithographic image forming systems in manydifferent configurations. As mentioned briefly above, multiple singlecolor/single ink modules may be provided to form multicolor imagesincluding pearlescent image elements or portions, or a single multiplecolor/multiple ink module may be provided to form the multicolor imagesincluding the pearlescent image elements or portions. In other words, noparticular limiting configuration is to be implied from the abovedescription and the accompanying drawings.

The exemplary depicted sequence of executable method steps representsone example of a corresponding sequence of acts for implementing thefunctions described in the steps. The exemplary depicted steps may beexecuted in any reasonable order to carry into effect the objectives ofthe disclosed embodiments. No particular order to the disclosed steps ofthe method is necessarily implied by the depiction in FIG. 4, and theaccompanying description, except where a particular method step isreasonably considered to be a necessary precondition to execution of anyother method step. Individual method steps may be carried out insequence or in parallel in simultaneous or near simultaneous timing.Additionally, not all of the depicted and described method steps need tobe included in any particular scheme according to disclosure.

As indicated in detail above, while the exemplary composition of theexperimental pearlescent ink shown in Table 1 provide a single exampleof an appropriate composition of individual materials that may be usedto comprise the disclosed pearlescent inks, compatible with variabledata lithographic image forming, it should be understood that one ofskill in the art may deviate from the experimental composition in orderto optimize the ink used to form the pearlescent image elements orportions on specified image receiving media substrates using the systemsand methods according to this disclosure. In other words, although theabove description may contain specific details, they should not beconstrued as limiting the claims in any way. Other configurations of thedescribed embodiments of the disclosed systems and methods are part ofthe scope of this disclosure.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations, or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by thefollowing claims.

We claim:
 1. An ink composition for use in forming variable pearlescentimage elements or portions on image receiving media substrates,comprising: a solid particle pearlescent pigment component in aproportion of at least 30% by weight, and having an average particlesize of greater than 15 microns, suspended in solution in the inkcomposition; and the solution comprising a functional acrylate monomer;at least one dispersant; a thermal stabilizer; and a photo initiatorsystem.